Such an offshore construction is known from WO 00/78599 in which a mooring buoy is disclosed which is anchored to the seabed in which the anchor chains are attached to the buoy via a pivoting chain receiving tube comprising a chain stopper by which the chain can be tensioned. By providing two orthogonal pivot axes for the chain tensioner, chain wear can be reduced and the tension in the chain upon movement of the buoy is decreased.
As is known generally, floating devices such as vessels or floating offshore structure, for example in the oil and gas industry, are moored to the seabed with one or more mooring lines. The floating device is kept on location because of the catenary effect of the mooring chains. A shift of the floating device leads to a lifting or lowering of the mooring chains, which leads to a counter effect striving to re-establish the original position of the floating device. The floating device is provided with a mooring chain connector assembly for each mooring chain, wherein the first pivot axis allows motions of the mooring chain in its catenary plane (so-called “in-plane motions”). It is also known to provide a second pivot axis, typically perpendicular to the first pivot axis, which second axis allows motions of the mooring chains in a transverse direction (so-called “out-of-plane motions”). In this manner fatigue problems in the mooring chain related to any motions of the mooring chain are minimized.
Mooring chain connector assemblies of this type are described for example in U.S. Pat. No. 6,663,320 filed by the applicant.
In U.S. Pat. No. 7,926,436 there is described a chain support hinged on two perpendicular axes which allows chain movement in two perpendicular planes. The chain support provides an improved arrangement to allow chain to be pulled through the center of the apparatus to a desired length after which the chain is removably secured to the chain support. In the known mooring chain connector assemblies, the dual axes are not coplanar which creates a moment from one articulation to the other.
The present invention provides a solution where moments between articulations will be avoided as well as load supported by the connector.
According to the present invention, the out of plane bending can be fully controlled and retensioning can be operated directly from the floating device. The solution proposed is ideal for weathervaning floating device but is also easily adaptable for spread moored floating device.
Further according to the present invention, the chain is protected against corrosion and the sling arrangement is simplified.